Method for conveying molten slag



May 22, 1934. T. BARTHOLOMEW 1,959,328

I METHOD FOR CONVEYING MOLTEN SIJAG I Filed March 10/1931 I v 4% M M 4%;

Patented May 22, 1934 UNITED STATES PATENT OFFICE 1,959,328 METHOD FOR CONVEYING MOLTEN'SLAG Tracy Bartholomew, Pittsburgh, Pa.

Application March 10, 1931, Serial No. 521,483

Claims. (Cl. 49-775) 10 places to convey the molten slag through conduits or guides in order to accurately deliver the slag to the desired point in the treating or forming apparatus.

The use of comparatively fiat conduits lined with metal or sand as has been the practice for conveying molten slag has certain disadvantages. The slag invariably sticks to the conduit and progressively builds up, even when a considerable stream of very molten slag is handled continuously, so that from time to time it is necessary to discontinue operations and clean out the conduit. Furthermore, and particularly when working with comparatively small streams of slag, it is impossible to maintain a uniform or controlled discharge from the conduit, as the quantity discharged is seriously affected by the loss of slag which adheres to the conduit, and also by the constantly decreasing cross-section of the slag stream. Where it is attempted to convey the. slag intermittently in small quantities through such a conduit, it is quite impossible to control the quantity and temperature or viscosity of the discharged portions.

I have found that molten slag does not adhere to cold metal and will slide or skid along same if sufficient inclination or momentum is provided. This I conceive to be due to the formation of a thin skin or film of non-fluid slag formed on the molten slag by the quick cooling when it comes into contact with the cold metal. I, therefore, prevent the adhering of the slag to my conduit by continuously cooling the same to a sufficiently low temperature. This cooling M of the conduit, which is made in the form of a chute or slide, is preferably accomplished by making the same of thin metal behind which is circulated water or other cooling medium.

In the accompanying drawing, which illustrates two embodiments of my invention Figure 1 is a longitudinal section through a slag conduit;

' Figure 2 is a plan view;

Figure 3 is a section on the line III-III of Figure 1;

Figure 4 is a section on line IV--IV of Figure 1; and

Figure 5 is a view similar to Figure 1 showing a modification in which water is supplied to the conveying surface of the conduit in order to produce porous slag.

Referring more particularly to Figures 1 .to 4 of the drawing, the conduit comprises a relatively thin sheet of metal indicated generally by the reference numeral 2 whichforms a con- 55 veying surface for the molten slag, the sheet of metal varying in cross-sectional shape from the receiving to the delivery end of the conduit. At the receiving or right-hand end of the conduit,

as viewed in Figure 2, the bottom 3 is substantially fiat and extends practically the whole width of the conduit. The slag is guided as it skids on the conduit by sides 4. The width of the fiat bottom 3 decreases as the delivery or left-hand end of the conduit, as viewed in Figure 2, is approached. The fiat portion 3 gradually diminishes in width until at the delivery end the conduit is substantially V-shaped in cross-section, as illustrated in Figure 4. A conduit so constructed provides a relatively large fiat bottom at the receiving end for receiving molten slag which is poured onto it at the'point indicated by the arrow 6 in Figure 1.

The formation of the delivery end of the conduit so that it is substantially V-shaped in crosssection insures accurate delivery of the molten slag at the desired point either to a slag treating or slag forming machine. The wider receiving end permits a certain leeway in charging or feeding the molten slag onto the conduit.

In order to prevent the slag from sticking to the conduit 2, the latter is provided with a jacket '7 which is welded or otherwise secured thereto. Water or other cooling medium is supplied to the cooling jacket through an inlet 8 and escapes through an outlet 9. The water inlet preferably is located at a'point directly under the point at which the molten slag is delivered to the conduit in order to insure that the conduit will be thoroughly cooledat this point so that the slag will not stick to it. I

The action of the water in the cooling jacket is to prevent adhesion of the molten slag, presumably by cooling the metal surface to such an extent that it forms a thinfilm or skin of non-fluid 105 slag on the bolten slag, which prevents the slag from sticking to the conduit. After the slag has been delivered from the conduit, the thin skin is remelted by the heat contained in the body of the slag. 1

In practicing the present method of conveying molten slag, a stream of molten slag is poured onto the conduit at the point represented by the arrow 6. The force of the stream of slag, taken in conjunction with the inclination of the conduit, is such that the slag skids along the cooled conduit and is discharged therefrom still in a substantially molten condition. This skidding action is distinguished from the usual flowing action of molten slag along a conduit which has only a slight inclination, or from the case where the molten slag is not supplied to the conduit with suflicient momentum to cause skidding. Where the conduit has only a slight inclination, or where the slag has insuflicient momentum, the molten slag in contact with the conduit freezes and gradually builds up a layer of solidified slag sticking to the conduit. This decreases the cross-sectional area of the conduit, thereby decreasing the quantity of slag which is delivered from the conduit in a given time. On the contrary, I obtain a skidding action of the molten slag along the conduit by cooling the conduit sufiiciently to prevent adherence of molten slag thereto, and by inclining the conduit sufficiently or by giving the molten slag suilicient momentum to accomplish this result. This prevents the building up of solidified slag on the conduit, the conduit in fact being entirely clear after molten slag has been skidded over it. The inclination of the conduit in some cases is such that if a continuous stream of molten slag is poured onto it, the slag discharged from the lower end of the conduit does not have the form of a continuous stream, but, on the contrary, is discharged therefrom in a succession of discrete or separate masses of molten slag having very thin films of solidified slag on their surfaces. are discharged at a higher velocity than the velocity of the stream poured onto the conduit.

The skidding of the molten slag over the conduit,

is so rapid that in the normal operation it takes only 'a fraction of a second for the slag to skid over the conduit from its point of application to the discharge end thereof. The present method is characterized by a rapid skidding of the molten effective cross-section of the conduit; the operation iscontinuousyand the discharged material may be. maintained quite uniform in quantity,

temperature, and viscosity. Where it is desired to produce dense slag products, it is not feasible 2 to apply water or other usual cooling medium directly to the conveying surface of the conduit,

...since if any cooling medium, such as moisture, '1which';wi ll'- form a gas on contact with molten slag, is" applied, it causes the slag to foam, and

= results ina porous product after the slag hasbe'en cooled. However, in some instances, it is desired .to produce porous slag products, that is, slag products such as building blocks having a large- These discrete masses delivery of the molten sl'ag to the conduit. Porous slag products may also be produced by delivering the molten slag through a conduit to a slag foam-' ing apparatus in which water is added to the slag and the mixture is stirred to produce a slag foam. The slag foam so produced 'in the apparatus is then conveyed through a conduit, as described, and is discharged into the molds to form the product.

In Figure 5 I have illustrated a conduit which is similar to that shown in Figure 1, except that it is provided at its upper end with a water supply pipe 12a. In this figure, parts corresponding to those shown in Figures 1 to 4 have been indicated by the same reference numerals with ana affixed. The water supply pipe is used only where it is desired to produce a porous slag product. The water from the pipe 12a Wets the conduit 2a so that when slag is poured onto the conduit it vaporizes the water and produces a porous molten slag. The purpose of adding water to the slag, whether the water is mixed with the slag before, after, or simultaneously with the delivery of the slag to the conduit is to produce a pourous slag. This porous slag is prevented from sticking to the conduit due to the cooling effect of the water circulating in the cooling jacket 7a.

My invention is applicable to the production of either dense or porous slag products. In both cases the slag is prevented from sticking to the conduit by the application of a cooling medium to a non-conveying surface of the conduit.

I have illustrated and described two embodiments of my invention. It is to be understood, however, that the invention may be otherwise embodied within the scope of the following claims.

I claim: 1

1. The method of conveying molten slag, which comprises skidding the substantially molten slag upon a surface which is cooled sufficiently to avoid adherence thereto, and discharging the slag therefrom while still in substantially molten condition. I

2. The method of conveying molten slag, which comprises skidding the substantially molten slag upon a metal surface which is cooled sufliiently to avoid adherence thereto, and discharging the slag therefrom while still in substantially molten condition.

3. The method of conveying molten slag, which comprises skidding the substantially molten slag upon a dry metallic surface, cooling said sur-- face sufficiently to prevent adherence of the slag, and discharging the slag therefrom while in substantially molten condition.

4. The method of conveying molten slag, which comprises skidding the substantially molten slag upon a wet surface to produce porous molten slag, cooling the surface sufiiciently to prevent ad herence of. the slag, and discharging the slag therefrom while in substantially molten condition.

5. The method of conveying molten slag, which comprises supplying molten slag toa cooled surface inclined at such an. angle, that the molten slag will skid along the surface, skidding lthe 6. The method of conveying molten slag, whichv comprises supplying molten slag to a cooled surface inclined at such an angle that the molten slag will skid along the surface, cooling the sur-f face sufliciently to form a thin skinonithe body of molten slag, skidding'themolten slag along the surface, and delivering the slag therefrom in substantially molten condition.

7. The method of conveying molten slag, which comprises supplying a continuous stream of molten slag to a cooled surface inclined at such an angle that the molten slag will skid along the surface, skidding the molten slag along the surface, and delivering a succession of discrete 9. The method of conveying molten slag, which comprises dropping molten slag onto a cooled wet surface inclined at such an angle that the molten slag will skid along the surface, skidding the molten slag along the surface, and delivering the molten slag therefromin substantially molten condition.

10. The method of conveying molten slag along a surface, which comprises cooling the surface sufliciently to prevent adherence of molten slag thereto, supplying molten slag to said surface with such momentum that it will skid along the surface, skidding molten slag along the surface,

and delivering theslag therefrom in substantially molten condition.

TRACY BARTHOLOME 

